1. Field of the Invention
The present invention relates to a carburizing treatment apparatus and a carburizing treatment method.
Priority is claimed on Japanese Patent Application No. 2005-273726, filed on Sep. 21, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
So-called carburizing treatments, in which an article to be treated composed of metal materials is increased in carbon content within a surface layer in order to quench and harden only the surface layer, are utilized in various treatment processes such as pack carburizing, liquid carburizing, gas carburizing, and vacuum carburizing and the like. Among these processes, the vacuum carburizing is often used in cases where the article to be treated is required be photoluminescent.
Vacuum carburizing is a process by which the article to be treated is increased in carbon content within the surface layer by a process such that, after the inside of a treatment chamber being made vacuum conditions, a slightly decomposed carburizing gas is supplied into the treatment chamber and, while such a state is maintained, the article to be treated is heated.
For example, Patent Document 1 and Patent Document 2 have disclosed a vacuum carburizing furnace by which the above-described vacuum carburizing process is used to provide a carburizing treatment to the article to be treated.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2004-27299
Patent Document 2: Japanese Unexamined Patent Application, First Publication No. 2002-357389
Incidentally, in the above-described vacuum carburizing furnace, how much extent the carburizing treatment is performed on the article to be treated depends on heating temperature, heating time, and temperature retention time and the like of the article to be treated. Therefore, in a case where a desired carburizing treatment is performed on the article to be treated, it is necessary to accurately control temperature inside the treatment chamber.
For this reason, in a conventional vacuum carburizing furnace, temperature inside the treatment chamber is measured by a temperature measurement means such as a thermocouple, thereby controls an output of a heater located inside the treatment chamber based on the measurement results of the temperature measurement means so that a desired temperature environment is attained inside the treatment chamber.
However, in the conventional vacuum carburizing furnace, temperatures are measured only at one spot in the treatment chamber to control the output of the heater on the basis of the measurement result. Therefore, according to a configuration of the article to be treated and variance in a loaded quantity of the article to be treated inside the treatment chamber, there may be a case where a failure in uniformly elevating temperatures of the article to be treated inside the treatment chamber arises.
In this case, variance in carburizing treatment progress is generated in the article to be treated, resulting in failure in providing a uniform carburizing treatment to the article to be treated.